Velocity & Brinell hardness

This is a discussion on Velocity & Brinell hardness within the Reloading forums, part of the Firearm Forum category; I'm considering using cast bullets with hardness of about 21 Brinnell in my .327 Fed. Mag, but I'm not sure if they'll take full-house velocities ...

I'm considering using cast bullets with hardness of about 21 Brinnell in my .327 Fed. Mag, but I'm not sure if they'll take full-house velocities without leading... Gas checks will likely make it a non-problem, but if I can do without them by using hard-cast bullets it means that I can buy more bullets for the same outlay of cash.

I know that there are a number of factors which can contribute to leading and that hardness (while a major factor) is not the only thing to consider, so I don't expect that there is a hard & fast answer that "above xxxx fps they will lead, below that you're okay", but even a ballpark estimate will be helpful.

ColoradoExpat, Actually, there is a direct correlation between bullet hardness and chamber pressure. As long as bullets are the correct hardness for the pressure you are loading, bore fouling will be minimal, no matter what the velocity. Here's a link to a document I posted in the Forum Library. It should give you some insight on bullet hardness. Click here: http://rugerforum.net/library/19869-...revolvers.html

For those velocities, a 10-15BHN alloy is all you need. I only need a massively HARD alloy like that for my .30-06 shooting at over 2200fps.
Let's be clear about things: a 5-8 BHN alloy is soft, a 12-15BHN is hard, a 18-22BHN is type metal and WAY harder than you need for any reasonable handgun--and, if you need an alloy that hard, you will almost certainly be happier with a 15BHN gas-check bullet.
FIT is everything and lube is second most important. I only shoot as-cast bullets that are at least 0.002" over the ACTUAL groove diameter of the barrel. Slug your barrel or have it slugged. Be sure the bullets you order are at least 0.001" over groove diameter. If you do get any leading with commercial bullets (and very hard bullets MUST be over groove diameter in my experience since they won't be bumped up to fill the bore), try a LIGHT tumble lube in Lee Liquid Alox.
For a revolver, you also need the bullets to be sized such that they are a very snug slip-fit in the cylinder's throats. Thus, if you had cylinder throats that were 0.312" and a groove diameter of 0.314", you probably can not successfully shoot lead in your gun. If your throats are 0.314" and the groove diameter is 0.312", you will probably have a gun that will LOVE lead bullets and hardness will not be a factor.
I have been reading about the correlation between pressure and lead bullet performance for about 30 years and NEVER found it to be true. Your gun will tell you what works.
I have shot over 2000 rounds of 200gn L-SWC in a T/C Contender .44 Mag with a hard alloy of about 14BHN and never had any leading, even at max.
In your case, I would predict that a 0.314-0.315" lead bullet would be near ideal, no matter what the hardness.

the 32 caliber revolvers are becoming my favorite. I have the ruger black hawk and a charter arms patriot in 327 federal, and shoot cast bullets in both. I have been using wheel weight + a small amount of tin and had no leading issues. normally a plain base bullet can be driven at around 1200 fps without leading. I have 3 32 magnums a ruger bisley, a 1895nagant that I reamed a 32 acp cylinder to the 32 magnum, and a shotgun I used a 30 caliber rifle barrel as a liner and made it into a 32 magnum. the only hard part of that project was the extractor on the 4th try I got one that works 100% of the time. the converted will shoot groups in the 2 inch range at 100 yards with the rcbs 100 gr. simi-wadcutter the saeco #325 is also a great choice. argie1891